So deal with this: Iraq does not exist anymore. Sure, there's a country called Iraq, and its leader is the same guy, Nouri al-Maliki, and it still has U.S. support, but it's not the same country.

The Islamic State (formerly ISIL) is not a ragtag group of rebels fighting in the hills. It's a relatively sophisticated group bent on creating a caliphate out of large chunks of Iraq and Syria, and it's fighting on both fronts and taking territory in both places.

When it swept over Mosul, for instance, it left the civil service intact - something America did not do in Iraq when we made our little incursion into the region. The Sunni Muslims there report mostly peace on the streets, open markets, a functioning financial system, all that.

Minorities have been persecuted, it's true. Anyone who isn't a Sunni Muslim is fair game - and even some Sunnis have been declared un-Islamic. Mosques built in honor of a particular Muslim hero are being torn down because the Islamic State doesn't believe that mosques should celebrate human beings at all, only God.

Sunnis and Shiites disagree over who should have been the successor to Muhammad after the prophet died. The guy that the Sunnis revere won, so most of the world's Muslims (something like 85 percent) are Sunnis. Sunnis and Shiites also differ on the Hadith, the textual commentary surrounding the Quran. And that's what they're fighting about - stuff that happened back in 632 C.E.

Religion can make you nuts. Have I said that before?

The Islamic State's form of Sunni Islam is not the variety generally practiced and preached in most of the world. The Quran talks about living together in harmony; the Islamic State banishes Christians from its territory because it wants nothing but Muslims in its caliphate. It kills people for a variety of offenses, including walking while Shiite. The leaders of the Islamic State are doing a very good impression of psychotic murderers.

And, most notably, their views on women are prehistoric. More liberal Muslim nations - Turkey, for instance, or Indonesia - do not demand that women wear veils or stay home. They don't beat them in the streets. But the jihadis do. They want their caliphate the old-fashioned way, with women as chattel and slaves.

The new caliphate, if it happens, would be a human rights disaster. It would also be a historical disaster, because jihadists don't seem to like history much. They bust up relics, because they can.

But because they're prehistoric doesn't mean they're dumb. They're using social media very effectively. They're gaining adherents around the world, and some of those adherents are going to join the big fight. The more powerful the caliphate, the worse it gets.

What can we do to rid the world of this evil? How can we prevent Iraq from getting overrun? The answer is, nothing. The United States has lost power and prestige everywhere, but notably in the Arab world. Benign Uncle Sam, the bringer of freedom (who was never quite that benign anyway), has been replaced by the Great Satan.

The war in Iraq did that. The war in Afghanistan did that. The specter of Americans bombing Muslim civilians, destroying Muslim villages, was just too much to bear. It was a fool's errand, but it was also an arrogant and ultimately meaningless display of power.

So, sorry, but we just can't go to war in Iraq again. The current government there, the fruit of all our nation building, is corrupt and violent. It persecutes Sunnis; it excludes them from meaningful positions in the government; it demonizes them. The police are often little more than thugs.

Is that the government the United States wants to preserve? We are supporting it diplomatically; we're invested in it, no matter how dreadful it is. That aligns us with Iran, another Shiite nation. To some extent it aligns us with Syria, whose government is fighting Islamic State rebels.

Iran and Syria? We are in rather heated conflict with both nations, so the irony is the size of a battleship. What the hell are we doing? We don't know. We also have another ally, Israel, also killing civilians. Wars everywhere. Do we have any power at all to alter this?

Some people say force of arms will do it. Perhaps it would be best to learn from experience on that one. Iraq and Afghanistan, where the Taliban again are on the march. We have another instance of prehistoric jihadis. They couldn't have done it without us.

I think we should take the hint. There are all sorts of awful situations around the world where our help would be useful. The Ebola epidemic, for instance; we could bring trained people and palliative medicine and expertise, all without an armed presence.

Of course, Africa has its own crazy jihadis. They're not going away. Deal with that too.

In which we contemplate the various depressing options in several countries.

"I should like it very much," said Alice, "but I haven't been invited yet." "You'll see me there," said jcarroll@sfchronicle.com.